Layered atlas and cartographic explorer for `https://crest-alpha-origin.pages.dev/maproom/`.

Concept:
Create `Crest Meridian Atlas`, a single-file editorial maproom focused on a believable fictional maritime shelf. The route should feel like a hybrid of a survey chart, expedition log, and operator console rather than a generic web map.

Atlas brief:
- Subject: a surveyed maritime basin with named banks, narrows, trench edges, convoy lanes, beacon stations, and field annotations.
- Tone: product precision with editorial map craft, restrained motion, crisp hierarchy, authored legends, and clear control states.
- Distinction: the interface should look like a curated maproom with parchment, ink, brass, and signal accents, not a commodity GIS dashboard.

Layer set:
1. Bathymetry contours and sounding bands
2. Transit corridors and drift/current routes
3. Survey annotations, beacons, and hazard notices
4. Optional weather-pressure overlay for atmospheric context

Navigation model:
- Primary map viewport with pan and zoom
- Pointer drag and wheel zoom
- Touch drag and pinch zoom
- Keyboard pan with arrow keys, zoom with `+` and `-`, reset with `0`
- Click or focus markers to open a location detail panel
- Guided route mode with previous/next controls and an autoplay option

Required interface systems:
- Layer toggles with persisted preferences
- Sector and annotation filters
- Crisp legend with visible state changes
- Selected-location detail card with coordinates, depth, status, and narrative note
- Memory of visited locations across reloads
- Responsive layout that preserves map usability on mobile

Data direction:
- Use believable spatial metadata with coordinates, depth figures, route intensity, survey years, and annotation categories.
- Keep the geography fictional but plausible.
- Include enough locations and overlays for the map to feel authored and worth exploring.

Visual direction:
- Dark vellum, chart-paper, and oxidised metal palette
- Sans-serif typography only
- Subtle gradients, grid lines, contour strokes, and annotation callouts
- Motion should be restrained and informative, never decorative